must specify at least 1 interface for attribute 'source' on a coclass
For certain attributes, you must pass an interface name as a parameter.
The following sample generates C3372:
#include <windows.h> [module(name="MyModule")]; [ object, uuid(373a1a4c-469b-11d3-a6b0-00c04f79ae8f) ] __interface IMyIface { HRESULT f1(); }; // to resolve, pass an interface name to the source attribute // for example, source(IMyIface) [ coclass, uuid(373a1a4d-469b-11d3-a6b0-00c04f79ae8f), source, default(IMyIface) ] class CMyClass { }; void main() { }